Why didn't mainstream media report Joe Biden's decline sooner?

From the show

In a new book, CNN's Jake Tapper and Axios' Alex Thompson look at Joe Biden's ill-fated re-election campaign and allege there was a cover-up of Biden's cognitive decline. Together they claim to have interviewed hundreds of people, but few were quoted on the record. Fair or not, the political right and left have criticized the authors of Original Sin: President Biden's Decline, Its Cover-Up, and His Disastrous Choice to Run Again, while the realizations in the book have also sparked reflection within in the press itself over how Biden's health was covered at the time. This week's guest is Richard Tofel, the former president of ProPublica, the nonprofit investigative journalism organization.